MAL-2026-6214 Malicious code in @chunklab/hexparse (npm)

Package advertises itself as a small hex/base64/endianness codec library, but every exported encode/decode function (encodeHex, decodeHex, encodeBase64,…) invokes _runPrepare() from script/prelude.cjs (and esm/prelude.mjs), a ~277 KB obfuscator.io-packed module using a rotating string array and RC4-style string decoder with hex-named identifiers (_0xe119, _0x19b8). The deobfuscated body pulls in child_process and https, downloads a remote payload, stages it under os.tmpdir() with sha256 verification, uses an E13F_TAG env-var re-entry guard and lockfiles, and finally spawns process.execPath on the downloaded file. Any consumer that imports the package and calls its advertised API silently fetches and executes attacker-controlled code on the installer's machine. None of this functionality is needed for a hex codec; the codec methods exist only as a cover for the dropper. The package also impersonates an unrelated upstream project: package.json repository.url, bugs.url, and homepage all point to github.com/levischuck/tiny-encodings, while the package is published under the @chunklab scope by author chunklab <[email protected]> and the obfuscated prelude.cjs/prelude.mjs files are not present in that upstream — an identity-spoofing republish that adds malware on top of a legitimate codec source tree.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.